Living with psoriatic arthritis (PsA) often means dealing with aches and pains. Many people with PsA report feeling joint pain in their hips, back, hands, knees, or feet, especially during disease flares. On top of this, roughly 35 percent of people with a psoriatic arthritis disease develop enthesitis — inflammation of the tissue that connects tendons or ligaments to bones. This symptom typically starts after someone develops PsA.

According to the National Psoriasis Foundation, people with spondyloarthropathies — which include PsA, ankylosing spondylitis, and axial spondyloarthritis — consistently experience enthesitis as a symptom. Other forms of arthritis, like rheumatoid arthritis and osteoarthritis, don’t usually involve enthesitis.

This article will cover the connection between PsA and enthesitis, as well as what you and your rheumatologist can do to help manage your symptoms.

What Is Enthesitis?

The human body contains more than 100 entheses, which are the places where tendons or ligaments connect with a bone. They all serve to anchor the soft tissues that bind bones to muscles, ensuring smooth movement. Enthesitis (also referred to as enthesopathy) occurs when an enthesis and its surrounding tissues become inflamed.

Enthesitis can happen to anyone. However, people with PsA are more likely to experience enthesitis and chronic (long-term) enthesitis. In addition to other PsA symptoms, enthesitis can cause musculoskeletal pain or limit your ability to move affected body parts.

Enthesitis mainly affects the points at which tendons and ligaments insert into bones. However, research suggests that enthesitis can affect any areas where hard and soft tissues come together, like joint capsules and fascia (connective tissue that surrounds and supports muscles, bones, and organs). Areas affected by enthesitis can become ropey in texture (a condition called fibrosis) or start to solidify through a process called ossification or calcification.

Enthesitis in Psoriatic Arthritis

PsA affects roughly 30 percent of all people with psoriasis. Enthesitis is a relatively common symptom of PsA. In fact, it is one of the hallmarks of PsA, and it’s related to more severe disease. Healthcare providers may use the presence of enthesitis to help diagnose PsA and differentiate it from other types of arthritis, like rheumatoid arthritis.

Other main signs of PsA include:

• Peripheral arthritis, which affects large and small joints in the hips, knees, wrists, elbows, feet, and ankles
• Spondylitis, which stems from inflammation of the spinal or sacroiliac joints or the joints connecting the sacrum and pelvis
• Dactylitis, also known as sausage digits, which causes swelling in the fingers and toes

Dactylitis is considered a form of enthesitis because it involves inflammation of the enthesis combined with inflammation of the joints and tendons.

If you have psoriasis and you also experience these symptoms, it might be a sign of PsA.

Symptoms of Enthesitis

Enthesitis often causes pain and limits movement (stiffness) in the affected joints. People with enthesitis often experience aches in their feet, knees, elbows, hips, and shoulders, although enthesis usually only affects one or two locations at a time.

Although enthesitis can affect any enthesis, it most commonly appears in:

• The Achilles tendon, which runs down the back of the heel
• The lateral epicondyles, the bony bump on the outside of the elbow
• The plantar fascia, the ligament connecting the heel to the front of the foot

As one MyPsoriasisTeam member shared, “My worst enthesitis is in my feet. I can’t be on my feet long, let alone walk very far.”

“Enthesitis is really bad right now. I cannot walk unassisted,” commented another member.

“Enthesitis is really bad right now. I cannot walk unassisted.”

— A MyPsoriasisTeam member

In severe cases, chronic inflammation can cause bone spurs, or abnormal bone growths, near the enthesis or within nearby ligaments. People with PsA and enthesitis may also notice pitting — small depressions — in their fingernails or toenails, or they may experience onycholysis, which is when the nails start to lift away from the nail bed. These changes can also appear in people without enthesitis.

Does Psoriatic Arthritis Cause Enthesitis?

PsA is not the sole cause or even a direct cause of enthesitis. Health experts don’t fully understand why, but people with PsA tend to have a lower threshold for developing enthesitis. Mechanical (physical) stress on the body, injury, or infections can all trigger long-term inflammation and ultimately lead to enthesitis. Healthcare providers believe enthesitis is better described as an early sign of PsA, rather than a direct result of the disease.

Enthesitis tends to correlate with worse health outcomes in people with PsA. In one study, researchers found that up to 52 percent of people with PsA-related enthesitis had moderate to severe PsA, compared to just 23 percent of those who didn’t have enthesitis. People with enthesitis were also more likely to experience other PsA symptoms, such as nail psoriasis and dactylitis.

One study found that up to 52 percent of people with PsA-related enthesitis have moderate to severe PsA.

There are several risk factors associated with PsA-related enthesitis. Those who have enthesitis with PsA tend to be young, have severe cases of PsA, or have a high body mass index (BMI).

People Without PsA Can Also Get Enthesitis

People who don’t have PsA can also develop enthesitis, typically after experiencing an injury or repetitive trauma. Lateral epicondylitis (tennis elbow) is a common enthesitis-related complaint that occurs after a person overuses their elbow with repetitive movements.

The main difference between enthesitis caused by mechanical problems and enthesitis with PsA is that, over time, enthesitis with PsA causes chronic inflammation, while mechanical enthesitis is caused by a single injury that can heal.

Generally speaking, enthesitis that’s related to overuse should heal if a person cares for their injury and avoids the repetitive movement that caused the inflammation. But for a person with PsA, enthesitis is often an ongoing problem.

Diagnosing Enthesitis With Psoriatic Arthritis

If you have psoriasis and start to feel pain in your feet, elbows, or hands, talk to your doctor immediately about the possibility of PsA. Delaying diagnosis and treatment by even six months could lead to worse joint damage and a lower quality of life.

If you have psoriasis and start to feel pain in your feet, elbows, or hands, talk to your doctor immediately about the possibility of PsA.

Diagnosing enthesitis is relatively straightforward most of the time. Your doctor will consider your medical history and symptoms. If you have psoriasis and nail pitting and are experiencing pain in a telltale location — such as your Achilles tendon — your doctor might be able to make a baseline diagnosis without further testing.

In some situations, your condition might not be as easy to define. For example, fibromyalgia can cause pain similar to enthesitis pain. To make a differential diagnosis (distinguishing between two or more conditions that have similar symptoms to determine the correct one), your doctor might conduct a few physical tests, such as moving your affected limb, or they may order an ultrasound to check for signs of enthesitis.

Treating Enthesitis With Psoriatic Arthritis

It’s important that you start exploring treatment options for enthesitis and PsA right away to prevent permanent joint damage. It’s also important because enthesitis is linked to an increased disease burden for people with PsA. The approach your healthcare provider recommends will usually depend on the severity of your condition.

Disease-modifying antirheumatic drugs (DMARDs) are commonly used to treat psoriatic arthritis. However, they may not be as helpful for enthesitis specifically. If you take a DMARD for psoriatic arthritis, make sure to talk to your healthcare provider about treatment options for your enthesitis.

Nonsteroidal Anti-Inflammatory Drugs

Your healthcare provider might recommend high doses of nonsteroidal anti-inflammatory drugs (NSAIDs) to treat your enthesitis. However, due to potential side effects, they may only recommend this type of treatment for a short period (up to one month). People with chronic kidney disease or a history of gastrointestinal issues are not good candidates for this type of treatment.

Steroid Injections

Local corticosteroid (steroid) injections may reduce disease activity and pain from PsA and enthesitis in a specific joint. These are different from oral steroid medications, which should be used carefully and only for the short term, as they may cause side effects.

Biologics

Biologic therapies are made from living organisms and help treat certain diseases by targeting the immune system. If NSAIDs aren’t sufficient and you have an active disease with enthesitis in multiple locations, your rheumatologist might suggest biologic therapies like a tumor necrosis factor (TNF) inhibitor or an interleukin inhibitor.

Other Treatments

In addition to the medications mentioned above, your doctor may prescribe oral systemic medications to treat enthesitis and psoriatic arthritis, including phosphodiesterase-4 (PDE4) and Janus kinase (JAK) inhibitors.

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